diff --git a/libc/include/sys/sysconf.h b/libc/include/sys/sysconf.h
index eb30faf..060ba7e 100644
--- a/libc/include/sys/sysconf.h
+++ b/libc/include/sys/sysconf.h
@@ -1,6 +1,14 @@
-/*
+#pragma once
+
+/**
+ * @file sys/sysconf.h
+ * @brief Historical synonym for `<sysconf.h>`.
+ *
  * This file used to contain the declarations of sysconf and its associated constants.
- * No standard mentions a <sys/sysconf.h>, but there are enough users in vendor (and potential ones
- * in the NDK) to warrant not breaking source compatibility.
+ * No standard mentions a `<sys/sysconf.h>`, but there are enough users in vendor (and
+ * potential NDK users) to warrant not breaking source compatibility.
+ *
+ * New code should use `<sysconf.h>` directly.
  */
+
 #include <bits/sysconf.h>